There is known a semiconductor device including a plurality of semiconductor elements each interposed between two opposed metal plates (see, for example, Japanese Patent No. 4702196). In this semiconductor device, the plurality of semiconductor elements are arranged on the metal plates side by side. These plurality of semiconductor elements are respectively a power transistor (IGBT) that constitutes an arm element of a power converter and a reflux diode connected in parallel with the power transistor, and each are bonded to the metal plates via a corresponding solder member and a corresponding metal block.
For the above-described semiconductor device, there is a metal plate in which grooves are formed on a bonding face, to which the metal blocks are bonded (hereinafter, referred to as grooved metal plate). The grooves allow redundant solder to flow thereinto and prevent spreading of the solder. The grooves each are formed on the bonding face of the grooved metal plate along the outer periphery of a region in which the corresponding solder member is provided, and are formed individually in correspondence with the metal blocks arranged on the metal plate. Each of the grooves for the metal blocks is formed in an annular shape on the bonding face of the grooved metal plate so as to have a size designed for the size of the corresponding metal block.
However, in the above-described semiconductor device, it is required to provide the grooves formed on the metal plate individually in correspondence with the metal blocks, so it is required to provide certain space between the metal blocks such that the grooves of the respective metal blocks do not overlap with each other on the surface of the metal plate. This leads to an increase in size in the direction of the metal plate in which, particularly, the plurality of metal blocks are arranged side by side (that is, the direction in which the plurality of semiconductor elements are arranged side by side), with the result that there is a concern that the size of the semiconductor device itself increases.